What are the three phases of vaccine testing?
What are the three phases of vaccine testing?
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Substantial research needs to be completed by scientists before any potential vaccine undergoes phased testing. Once it gets to that stage, there are three research phases of trials that take place before the vaccine can be deployed for use. During the first stage (Phase I), the new vaccine is provided to small groups of people—the first time the vaccine is tested in humans. The second stage (Phase II) involves testing the vaccine on people who have similar characteristics (such as age and physical health) to the target population, or the group for which the vaccine is intended. The goal of this stage is to identify the most effective dosages and schedule for Phase III trials. The final stage (Phase III) provides the vaccine to thousands of people from the target population to see how safe and effective it is. Once the vaccine clears this last stage, the manufacturer can apply for a license from regulatory authorities (like the FDA) to market for human use. Sometimes medications that have already been approved by the U.S. Food and Drugs Administration in clinical trials will enter into a Phase IV trial. This phase focuses on potential side effects from the vaccine or medication that were not seen in the first three phases. This phase also helps researchers understand how well a vaccine works over a longer time frame and how safe it is, often with thousands of people over several years. Phase IV is also called a 'post-marketing surveillance' trial.
Substantial research needs to be completed by scientists before any potential vaccine undergoes phased testing. Once it gets to that stage, there are three research phases of trials that take place before the vaccine can be deployed for use. During the first stage (Phase I), the new vaccine is provided to small groups of people—the first time the vaccine is tested in humans. The second stage (Phase II) involves testing the vaccine on people who have similar characteristics (such as age and physical health) to the target population, or the group for which the vaccine is intended. The goal of this stage is to identify the most effective dosages and schedule for Phase III trials. The final stage (Phase III) provides the vaccine to thousands of people from the target population to see how safe and effective it is. Once the vaccine clears this last stage, the manufacturer can apply for a license from regulatory authorities (like the FDA) to market for human use. Sometimes medications that have already been approved by the U.S. Food and Drugs Administration in clinical trials will enter into a Phase IV trial. This phase focuses on potential side effects from the vaccine or medication that were not seen in the first three phases. This phase also helps researchers understand how well a vaccine works over a longer time frame and how safe it is, often with thousands of people over several years. Phase IV is also called a 'post-marketing surveillance' trial.
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What our experts say
Substantial research needs to be completed by scientists before any potential vaccine undergoes phased testing. Once it gets to that stage, there are three research phases of trials that take place before the vaccine can be deployed for use. During the first stage (Phase I), the new vaccine is provided to small groups of people—the first time the vaccine is tested in humans. The second stage (Phase II) involves testing the vaccine on people who have similar characteristics (such as age and physical health) to the target population, or the group for which the vaccine is intended. The goal of this stage is to identify the most effective dosages and schedule for Phase III trials. The final stage (Phase III) provides the vaccine to thousands of people from the target population to see how safe and effective it is. Once the vaccine clears this last stage, the manufacturer can apply for a license from regulatory authorities (like the FDA) to market for human use.
Sometimes medications that have already been approved by the U.S. Food and Drugs Administration in clinical trials will enter into a Phase IV trial. This phase focuses on potential side effects from the vaccine or medication that were not seen in the first three phases. This phase also helps researchers understand how well a vaccine works over a longer time frame and how safe it is, often with thousands of people over several years. Phase IV is also called a 'post-marketing surveillance' trial.
Substantial research needs to be completed by scientists before any potential vaccine undergoes phased testing. Once it gets to that stage, there are three research phases of trials that take place before the vaccine can be deployed for use. During the first stage (Phase I), the new vaccine is provided to small groups of people—the first time the vaccine is tested in humans. The second stage (Phase II) involves testing the vaccine on people who have similar characteristics (such as age and physical health) to the target population, or the group for which the vaccine is intended. The goal of this stage is to identify the most effective dosages and schedule for Phase III trials. The final stage (Phase III) provides the vaccine to thousands of people from the target population to see how safe and effective it is. Once the vaccine clears this last stage, the manufacturer can apply for a license from regulatory authorities (like the FDA) to market for human use.
Sometimes medications that have already been approved by the U.S. Food and Drugs Administration in clinical trials will enter into a Phase IV trial. This phase focuses on potential side effects from the vaccine or medication that were not seen in the first three phases. This phase also helps researchers understand how well a vaccine works over a longer time frame and how safe it is, often with thousands of people over several years. Phase IV is also called a 'post-marketing surveillance' trial.
Context and background
There is growing interest in understanding the process of testing vaccines, to get a sense of how long it may take before there is a widely-available vaccine to address the COVID-19 pandemic. There have been many press releases and articles about vaccines in development and the start of human trials, yet health experts at the U.S. Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) warn that it will take time to screen out ineffective and unsafe vaccines as well as to prepare for vaccine use at scale. People are eager for a vaccine to be ready soon for many reasons, including protection of human life, economic recovery, reducing educational interruptions, and lifting restrictions on activities that people enjoy.
There is growing interest in understanding the process of testing vaccines, to get a sense of how long it may take before there is a widely-available vaccine to address the COVID-19 pandemic. There have been many press releases and articles about vaccines in development and the start of human trials, yet health experts at the U.S. Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) warn that it will take time to screen out ineffective and unsafe vaccines as well as to prepare for vaccine use at scale. People are eager for a vaccine to be ready soon for many reasons, including protection of human life, economic recovery, reducing educational interruptions, and lifting restrictions on activities that people enjoy.
Resources
- Vaccine Testing and the Approval Process (U.S. CDC)
- Vaccine Testing and the Approval Process (U.S. CDC)
